1. Field of the Disclosure
The present disclosure relates to devices and methods for selective actuation of wellbore tools. More particularly, the present disclosure is in the field of control devices and methods for selective firing of a gun assembly.
2. Description of the Related Art
Hydrocarbons, such as oil and gas, are produced from cased wellbores intersecting one or more hydrocarbon reservoirs in a formation. These hydrocarbons flow into the wellbore through perforations in the cased wellbore. Perforations are usually made using a perforating gun loaded with shaped charges. The gun is lowered into the wellbore on electric wireline, slickline, tubing, coiled tubing, or other conveyance device until it is adjacent the hydrocarbon producing formation. Thereafter, a surface signal actuates a firing head associated with the perforating gun, which then detonates the shaped charges. Projectiles or jets formed by the explosion of the shaped charges penetrate the casing to thereby allow formation fluids to flow through the perforations and into a production string.
In many situations, a perforation activity may utilize an assembly of several guns. In such situations, it may be advantageous to have the ability to determine whether all the guns in a gun assembly have fired. One such situation is where two or more guns of a perforating gun assembly include firing heads that are configured to activate at the same applied pressure. Variances in operating equipment and/or design tolerances may cause the firing heads to respond to slightly different applied pressures. Also, the firing heads may be configured to activate at different applied pressures. In either case, it may be advantageous to be able to fire the guns in a manner that ensures all firing heads have sufficient time to activate upon application of pressure. Another situation is where the firing sequence does not permit a clear detection of the firing of each gun in the assembly. If the non-firing of a gun can be easily determined, a firing sequence can be retrieved to cause a firing of any gun that did not fire. Moreover, if less than all the guns have fired, certain procedures may be used at the surface when retrieving the guns to prevent an unintended detonation of any gun that has not fired.
The conventional firing systems for various reasons, such as capacity, reliability, cost, and complexity, have proven inadequate for these and other applications. The present disclosure addresses these and other drawbacks of the prior art.